package linkedlist;

import jdk.nashorn.internal.runtime.ListAdapter;

import java.util.List;

public class MyLinkedList {
    static class ListNode{
        public int val;
        public ListNode prev;
        public ListNode next;

        public ListNode(int val){
            this.val = val;
        }
    }

    public ListNode head;//标记头
    public ListNode last;//标记尾

    //头插法
    public void addFirst(int data){
        ListNode node = new ListNode(data);
        if(head == null){
            head = node;
            last = node;
        }else{
            head.prev = node;
            node.next = head;
            head = node;
        }
    }
    //尾插法
    public void addLast(int data){
        ListNode node = new ListNode(data);
        if(head == null){
            head = node;
            last = node;
        }else{
            last.next = node;
            node.prev = last;
            last = node;
        }
    }
    //任意位置插入
    public void addIndex(int index,int data){
        if(index < 0 || index > size()){
            System.out.println("index不合法");
        }
        if(index == 0){
            addFirst(data);
            return;
        }
        if(index == size()){
            addLast(data);
            return;
        }
        ListNode cur = searchIndex(index);
        ListNode node = new ListNode(data);
        node.next = cur;
        node.prev = cur.prev;
        cur.prev.next = node;
        cur.prev = node;
    }
    public ListNode searchIndex(int index){
        ListNode cur = head;
        while(index > 0){
            cur = cur.next;
            index--;
        }
        return cur;
    }

    public void display(){
        ListNode cur = this.head;
        while(cur != null){
            System.out.print(cur.val+" ");
            cur = cur.next;
        }
    }

    public boolean contains(int key){
        ListNode cur = this.head;
        while(cur != null){
            if(cur.val == key){
                return true;
            }
            cur = cur.next;
        }
        return false;
    }

    //删除第一次出现关键字为key的节点
    public void remove(int key){
        ListNode cur = head;
        while(cur != null){
            if(cur.val != key){
                cur = cur.next;
            }else{
                if(cur == head){
                    head = cur.next;
                    head.prev = null;
                }else{
                    cur.prev.next = cur.next;
                    if(cur.next == null){
                        last = cur.prev;
                    }else{
                        cur.next.prev = cur.prev;
                    }
                    return;//不加return空指针异常
                }
            }
        }
    }
    //删除所有关键字为key的节点
    public void removeAllKeys(int key){
        ListNode cur = head;
        while(cur != null){
            if(cur.val != key){
                cur = cur.next;
            }else{
                if(cur == head){
                    head = cur.next;
                    head.prev = null;
                    cur = head;
                }else{
                    cur.prev.next = cur.next;
                    if(cur.next == null){
                        last = cur.prev;
                        cur = null;
                    }else{
                        cur.next.prev = cur.prev;
                        cur = cur.next;
                    }
                }
            }
        }
    }

    public void clear(){
        ListNode cur = head;
        while(cur != null){
            ListNode curNext = cur.next;
            cur.prev = null;
            cur.next = null;
            cur = curNext;
        }
        head = null;
        last = null;
    }


    public int size(){
        int count = 0;
        ListNode cur = head;
        while(cur != null){
            count++;
            cur = cur.next;
        }
        return count;
    }
}
